High quality paper for inkjet printing may have one or more coating layers intended to improve printing quality. Coated inkjet paper has a coating layer including a substantial amount of pigment and a binder for the pigment. After drying, the coating forms a microporous absorptive layer on the surface of the paper.
The coating layer composition may also be tailored to react with the colorant in the inkjet ink. Water based inkjet inks may have their color provided by either a dye or pigment. A dye is provided in solution while a pigment is provided in dispersion. A paper coating layer can be adapted for use with either or both types of colorant.
Coated paper adapted for printing with inkjet inks having a dye as the colorant are typically formulated with a pigment, a binder for the pigment and a cationic fixative. The binder is typically polyvinyl alcohol (PVOH), which is dissolved in water to make a polymer solution before addition to the coating recipe. The cationic fixative is typically a soluble polyvalent polymer. The cationic fixative reacts with the anionic dye to fix the dye by precipitation. Some examples of coating compositions of this type are described in U.S. Pat. Nos. 6,656,545 and 6,713,550.
Coated paper adapted for printing with inkjet inks having a dispersed pigment as the colorant are typically formulated with a pigment, a binder for the pigment and a salt with a polyvalent metal ion. The salt, typically calcium chloride (CaCl2), provides a metal ion that fixes the pigment by dispersion breakage.
So-called “universal” inkjet paper is adapted for printing with both dye and pigment based inkjet inks and contains both a cationic fixative suitable for fixing a dye and a salt suitable for fixing a pigment.